The society has recently demanded a reduction in carbon dioxide emission for the purpose of resource conservation, energy conservation, and environmental protection. For automobiles, various measures such as weight reduction and utilization of electric energy have been examined. This requires tires for automobiles to have improved abrasion resistance for resource conservation. Also, it is desired that tires have a longer life to improve the properties such as durability.
For example, it is known that the abrasion resistance can be improved, for example, by reducing the amount of sulfur vulcanizing agent in the rubber composition. However, this method causes deterioration of fuel economy and reduction in rigidity (hardness). Thus, these properties are difficult to achieve simultaneously.
Patent Literature 1 proposes to adjust the ratio between the sulfur vulcanizing agent content and the vulcanization accelerator content so as to improve the performance of a tread in terms of heat build-up, abrasion resistance and the like. However, this method still leaves something to be desired in terms of improving the abrasion resistance, heat aging resistance, processability, and fuel economy in a balanced manner.